Just wanted to report how everything went: As suggested by several FTers, NZ check-in staff refused to check my luggage through as I was booked on two separate PNRs. I personally find this policy ridiculous (especially as my trip only consisted of *A operated flights), but there we go.

SYD was a complete zoo. I did make my connection, but I would have never made it without Express Path both on arrival and departure.

I had fortunately kept an (unused) express pass from another flight to use on arrival, but even then it took me nearly an hour to work my way through the arrival procedure. Regular queues were a 50m long and went through the entire luggage belt area, could have easily taken several hours.

Departing was fairly easy, took my about 20min to go through passport control and security using Express path (which still is among the longest times I´ve experienced at any airport as an Elite).

Even though I made my 2:30h connection, this is not something I would recommend to anyone.